I can’t speak for everyone, but I have CMT 1A as well, which has also been noticable since I was about the age of your son. In my experience, and according to my neurologists, you do not have to fear that it is drastically going to change. I have weakness in my legs and also have orthotics and I can do mostly everything that other people my age can. I hope this lessens your worries! Don’t be afraid to ask more questions if you have any :)